Preparation of paving compositions



Patented May 26, 1 942 PREPARATION OF PAVING COMPOSITIONS (lirarles Mack, Sarina, Dntario,

@anada, assignor to Standard Oil Development Company, a corporationoi Delaware No, Drawing. Application June 4, i937,

- Serial No. 146,371

12 Claims. (or. 106-269) This invention relates to improvements in new ing mixtures and more particularly it relates to improvements in the-adhesion of the bituminous constituents and the mineral aggregate.

of water-soluble salts of metal'bases.

determined by a study of the behavior of the treated aggregates towards wetting agents" in the presence of water, the wetting agents used In the laying of bituminous pavements, the- 5 being the bottoms obtained on subjecting oximineral aggregates used are those that are most dized paraffin wax to vacuum distillation at high available in the region where the pavements K temperatures, tar still pitch, (a residue of the are being constructed. It has often been found If fgrmed bfi' partial (gaging) andf degdrats. in the past that some bituminous pavements e c X was n a were 01m 0 begin i ravel' badly during t first winter and 10 be effective were the'watersoluble metallic salts 0 to pieces on examining these pavements Of the metals 0f the quahtative analytic silver, it is generally found that the bottom part of the 513 3 ig g i i 3 eg g which avements in contact with moisture from the v Foundation were washed'e'ntirely free of asphalt, mainly contain smeahydrochloric acid m also or that surface moisture disintegrated the mixbe used to extract f anmnes and thereby reduce ture. An analysis of these aggregates disclosed ?g g z gi z 532 3 2; i gg g the presence of sodium and potassium inmost aggregate g bituminous? s 3; every Tms was especmny tliue is particularly true when the aggregates had great variety of mineral aggregates irrespective weathered or contain same clay The effects of of their main constituents. Aggregates, such as treated nune'ral aggregates determined by of flint, beach sand, clay, limestone or silica, adding 30 cc of Water to each 10 grams bf an were also found to contain sodium and potasaggregate an amount of the salt 801m 5mm and thereby have hlgher pH V than tion (containing 0.1 mol per liter) was added and aggregates of the same P free of alkahesshaken so that the aqueous phase had a low An object Of this invemmn is to improve pH value, preferably of 6.8 after adsorption.

adhesion between bituminous materials and ag- The treated aggregates e then' shaken with gregates that have high P values' other 10 cc. of a 5% solution of the wetting agents jects' of the invention w ll be understood on di olved in naphtha, and the amount of ag-' reading the following description of the process. gregate coated by the n agent w esti; According to this invention, the adhesion of ated from the aggregate remaining in' the the bituminous constituents of a paving mixaqueous phase after settling. a

ture and the mineral aggregate is improved by The proportion of the surfaces of the various tr i h min ral regate with a base exaggregates covered upon being treated with. the change agent such as aqueous solutions .35 Various combinations ofinorganic salts and wetting agents is as follows:

TABLE 1 The per cent figures show how much of the surfaces of the aggregates were coated by the wetting agents Flint, pH 7.7 Beach sand, pH 8.4 Clay, pH 8.6 Limestone, pH 9.0 Base exchange agent i A B O A B O A B 0 A B .0

Per Per Per Per Per Per Per Per Per Per Per cent cent ce'nt cent cent cc'nt cent cent cent cent cent 0 0 0 0 0 30' 30 ,30 0 0 0 100 100 0 10 20 100 100 20 20 30 40 40 '50. 10 10 100 100 100 100 100 60 60 70 40 100 100 10 l0 10 50 50 10 20 100 100 40 40 50 40 40 40 20 I 20 100 80 30 60 10 70 0 I0 100 100 100 90 -100 90 50 '100 3 100 100 100 100 100 100 100 100 100 100 l 100 100 60 80 60 60 60 50 0 0 100 100 20 I 20 10 40 40 40 0 0 100 100 30 2Q. 20 40 50 40 0 0 A-Still B-Tar st pi ch 0 -Degras.

bofitoliis of vacuum distilled oxidized parafliu.

assesses The following Table 2 shows what bases were effective with aggregates of various pH values:

aluminum chloride, lead acetate, and lead nitrate. Wetting agents were found to materially TABLE 2 Base exchange agent Wetting agent FLI II, PH 7.7

H drochloric acid Tar still pitch, degras. 03 gulph5t9 Oxuiaced parailin bottoms, tar still pitch, degras. Bil i o. 2182 213 hate.. 'lar still pltch, degras. Mercur c Oxidized paraflln bottoms, tar still pitch, degras.

. Oxidized paraflln bottoms, tar still pitch.

Aluminum chlori OXldIlJZGG paraflin bottoms, tar still pitch, degras.

Oxidized paraflln bottoms, tar still pitch, dcgras. Oxidized parafiin bottoms, tarstill pitch, degras.

. Oxidized parai lln bottoms, tar still pitch, degras.

Ferrous sulphate. Do. Ferric chloride Do.

BEACH SAND, PH 8.4

Silver nitrate v Lead acetate. 'Iar still pith, deg-res Lead nitrate CLAY, PH 8.6

Lead acetate 'lar still pitch Lead nitrate LIMESTONE, PH 9.0

Lead acetate. 'lar still pitch.

Lead nitrate Oxidized paraflln bottoms, tar still pitch, dgras.

the aggregates increases, the number of inorganic salts which bring about the desired effect decreases.

According to this invention, the mineral aggregate for each 1000grams of the aggregate is coated with 30 cc. of water in which 0.1 to 3% of the" base exchange agent based on the mineral aggregate is dissolved, the moist aggregate mixed with a bituminous material, such as liquid asphalt, and used as a'paving mixture. The aggregate can be dried before applying the asphalt.

The adhesion was determined by immersing the moist mixture in water immediately after preparation. The aggregates used were beach The results indicate that as the pH value Of3o improve the adhesion between the asphalt and the treated aggregate, the preferred wetting agents being tar still pitch and calcium, zinc or lead soaps prepared from naphthenic acids, for example those derived from Colombian fuel'oil. The asphalt was 90 parts of cracking coil tar reduced to a softening point of 75 F. cutback with 10 parts of naphtha. Other asphalts and wetting agents may also be used.

The following table shows the effects of wate upon alkali-bearing aggregates coated with asphalt containing wetting agents and upon alkali-bearing aggregates treated with base exchange agents and coated with asphalt contain ing wetting agents.

TABLE 3 Efiect of water on the asphalt coating of a mineral aggregate "l e and per cent of Wetting agents used organic. treating agent based on aggregate Tar still pitch Ca naphthenate Pb naphthenate Zn naphthenate BEACH GRAVEL AND SAND All displaced- All displaced. Mostly displaced. Most! displaced. Mostly displace Partially displ Partially displace Partia ly displaced. All displaced.. All displaced... Mostly displaced. Mostly displaced. None displaccd. None displaced. None displaced None displaced. .----di) -.ClO d0 Do.

LIMESTONE None All displaced Displaced Displaced Displaced, 0.087 AgNQa- .--..d .d0 Do. 0.05% A101.-- d0. no. 0.11 o PbACL None displaced.. None displaced None displaced. 0.1% Pb (N01): -.dO D

sand and gravel graded to maximum density,

and limestone ranging from to'l inch in size. The preferred inorganic salts were silver nitrate,

It was found that about 0.1% of lead salts was suflicient to insure good adhesion of the bituminous constituents and the treated mineral a greconstituents and the treated mineral aggregate further, the mixture were mechanically shaken with water, where the time in minutes required to remove the asphalt from the ravel by mematerials for each run were mixed by hand with shovels in ten batches of 300 lbs. each in a larxe iron pan., The ingredients were heated and treated as shown below, after which they were thoroughly mixed.

chanical wear is determined. The results ob- Run No. 1.---Asphalt heated to 150 F. Ag tained wereas follows: i gregate heated to 130 F.

" n Team 4 Y I Wettin a cntln as bait Watercong g p Amount and typo oilead salt used tentgfag- T ml Pb h Z h gre a are 'aua na nna None pitch thena t e thena te thenete Percent Minutes llrfinutea lllinum M-nutea Minutes None Nonc 0.11%1ead acetate 3 110 0.10% lead nitrate....' ano no The improvement in adhesion by the addition of slaked lime (0.5%) to a weathered pit gravel containing clay is illustrated by the following 7 table, where the time in minutes required to remove the asphalt from the gravel by mechanical wearis shown:

The quantities of wetting agent in the asphalt is also of importance and the effects of the.

amount of wetting agent in the asphalt between 0.5 and 3% was determined. The wetting agents investigated were calcium and lead naphthenate. The durations of time in minutes necessary to start displacement of the asphalts from the sands Run No. 2.-Asphalt heated to 150 F., lead naphthenate' added. Aggregate treated with lead nitrate solution, dried and heated to F.

Run No. 3.Asphalt heated gate heated to 180 F.

Run No. 4.Asphalt heated to 200 F. cal-- cium naphthenate added. Aggregrate treated Mix. No. 2 was cured for 132 hours at 100 F.

A wheel upon which a rubber tire was mounted was used in this test. The total load on the tire during the successive stages of the test was 980 lbs. which was distributed over a bearing area of 15.75 sq. inches.

are shownas follows: 5 After each mixture was laid, it was compacted i TABLE 5 Displacement of asphalt from sand Per cent wetting agent in asphalt Per cent lead nitrate on aggregate -Water content Wetting agent Per cent Per cent Minutes Minutes Minutes Minutes Minutes 0.0 0 Ca naphthenate 30 30 30 0.1 .do 80 130 0. 0 0 Pb naphthenato 30 I 35 40 40 0.1 3 .-do 60 120 170 Asphaltic materials having higher melting points may be used according to this invention. Other wetting agents incorporated in the asphalt may also be used, for example fatty acids and esters of higher fatty acids and high molecular weight monohydric alcohols.

'mixturesic'onsisted of 10% of bottoms of cracking coil tar distillate and 90% of 75 F. softening point cracking coil tar asphalt. The asphalt used in the remaining two testswas a cracking coil tar asphalt of 75 F. softening point. The

by rotating the wheel for 500 revolutions at a speed of 2.4 miles per hour and 1500 revolutions at a speed of 3.6 miles per hour. Profiles taken at intervals of 500 revolutions showed compac tion to be complete after this period, after which the wheel was operated for a further 1500 revolutions at a speed of 2.4 miles per'hour to observeany surface wear or change in profile.

The surface of the mixture was then flooded with water at 77 F. to a depth of 3", and the wheel was operated in low gear until failure took place.. The point of failure is reached after 50 lbs. of material has been removed by the test.

' At regularintervals during the test the water was drained from the track, and the aggregate which had been displaced by the action-of the wheel was removed. The number of revolutions to 200 F. Aggrerequired under water to bring about failure in fin wax bottoms, degras, calcium naphthenate,

the runs was as follows:

zinc naphthenate and lead naphthenate.

Tenn: 6

Number of -revolutlons 1'01 failure 1 96 beach gravel graded to maximum denslty+4% cutback asphalt-cured for 120 hrs. at 100 F 1 500 2 953 1 beach gravel, graded to maximum density, treated with 0.1% lead nltratc+3.9l% cutback asphslt to which was ad ad 0.08% lead na hthenate and cured ior 132 hours at 100 F 21, 000 3 96% beach gravel graded tomaximum density 4% 75 F. B. P. cracking coil tar asphalt. No curing was required. 10, 500 4 95.91% beach gravel, graded to maximum dens ty, treated with 0.1% lead nitrate+3.9i% 75 F. S. P. cracking coil tar asphalt to which was added 0.08% calcium naphthenate. No curing was required 37, 000 5 95.91% beach gravel, graded to maximum density, treated with 0.1% end mtratc-i-S.91% 75 F. S. P. cracking coil tar asphalt to which was added-0.08% lead nsphtbenate. N o curing was required 70, 000

From the above results it is shown that the addition of wetting and base exchange agents increases the number of revolutions for failure from 1,500 to 21,000 wherea cutback asphaltis used, and from 10,500 to 37,000 and 70,000 where a semi-solid asphalt is used.

It is not the intention to limit this invention to the specific examples given. It is the applicentjs intention to claim this invention as broadly as the prior art permits.

I claim:

1. A paving composition comprising a min-- eral aggregate coated with a water-soluble salt selected from the group consisting of silver, copper, aluminum and iron groups and bonded with an asphalt containing a wetting agent selected from the group consisting of oxidized paraffin wax bottoms, tar still pitch, degras, calcium naphthenate, zinc naphthenate, and lead naphthenate.

2. A paving composition comprising a mineral aggregate coated with lime and bonded'with an asphalt containing a wetting agent selected from the group consisting of oxidized paraffin wax bottoms, tar still pitch, degras, calcium naphthelrgate, zinc naphthenate, and lead naphthena 3. A paving composition comprising a mineral aggregate coated with an aqueous solution of a water-soluble salt selected from the group consisting of silver, copper, aluminum and iron, the water evaporated and the dry mineral aggregate bonded with an asphalt containing a wetting agent selectedfrom the group consisting of oxidized paraifin wax bottoms, tar still pitch, degras, calcium'naphthenate, zinc naphthenate, and lead naphthenate.

4. A paving composition coated with a water"- soluble salt of lead and bonded with an asphalt containing a wetting agent selected from the group consisting of tar still pitch, oxidized paraf- 5, A paving composition comprising a mineral aggregate coated with a water-soluble salt of lead and bonded with an asphalt containing calcium naphthenate in solution.

6. A paving composition comprising a mineral aggregate coated with a water-soluble salt of lead and bonded with an asphalt containing lead n'aphthenate in solution.

7. A. paving composition comprising a mineral aggregate coatedwith a water-soluble salt of lead and bonded with an asphalt containing zinc naphthenate in solution.

8. A paving composition comprising a mineral aggregate coated with lead nitrate and bonded with an asphalt containing a wetting agent selected from the group consisting of oxidized parafiin wax bottoms, tar still pitch, degras, calcium naphthenate, zinc naphthenate, and

lead naphthenate.

9. A method of preparing a paving composition 'which comprises coating a mineral aggregate with a water-soluble salt of lead and bonding the'rfiineral aggregate with an asphalt containing calcium naphthenate.

10. A method'of preparing a paving composition which comprises coating a mineral aggregate with a water-soluble salt of lead and-bonding the mineral aggregate with an asphalt containing lead naphthenate.

11. A method of preparing a paving composition which comprises coating a mineral aggregate with a water-soluble salt of lead and bonding the mineral aggregate with an asphalt containing zinc naphthenate.

12. A method of preparing a paving composition which comprises coating a mineral aggre- 

